Irmscher grew up on Marlowe. At the age of 18, he was without any real prospects, and he made his living by going door to door and selling unregulated fones, getting enough money to pay the rent and take girls out. One such girl he came into contact with was Mary Lou. The two met in a stim bar, and after a whirlwind night he got her contact information. He took a picture of her with one of his fones and kept it stored.
A few days later, Irmscher knocked on the door of a Dominion Marine Corps recruiter, Sergeant Robert Maury. Maury wasn't interested in the boy's wares, but the conversation didn't end. Maury was able to compel Irmscher to join the DMC and three days later, Irmscher was bound for boot camp on Turaxis II. His held was filled with stories of heroic combat, legendary R&R trips, and the glory of earning medals.
He was assigned to Rho Squadron, and would often bring up pictures of Mary Lou to show to his squadmates. They teased him for his naïve mouth, but he held on to her as an ideal of what he could have after the war was over.
During the Battle of Lawndale 12, Rho Squadron was assigned with defending the communications relay of Lawndale 12. Irmscher and his comrades took positions in the trenches defending the communications relay. A horde of zerglings swarmed their position, in spite of the defenders outnumbering them. However, they managed to get into the trenches, and one sliced Imrscher open. His suit attempted to lock down the sealed arteries, but it was too late. The zerg were repelled, but Irmscher died, his last words being "Mary Lou."